This invention relates to the manufacture of cheese flavour powder.
Cheese flavour powder is conventionally produced by macerating a selected cheese or mix of cheeses, rendering in measured amounts of hot water together with various other food grade ingredients, and raising the mix to pasteurising/emulsification temperatures prior to feeding to a conventional spray drier from which the resultant powder is collected and bagged.
This conventional process suffers from a number of disadvantages as follows:
1. Cheese varies considerably in flavour profiles and physical properties and requires careful selection and processing in order that end flavour and physical properties are sufficiently protected to meet consumer requirements.
Under the most controlled conditions, end flavour is variable and its intensity cannot be assured.
2. For large scale manufacture of cheese flavour powder a considerable inventory of cheese is required, creating cost pressures in financing and storing bulk cheese for long periods under controlled temperatures demanding refrigeration, and in costly insulated storage areas.
3. Labour costs of the overall process are high; cheese must be decartoned, unwrapped, cut and macerated prior to feeding to the mixing tank.
4. Addition of ingredients such as whey powder to the formulated mix requires the addition of more water before drying at a solids concentration of about 40%, thereby substantially increasing energy costs of batch preparation and eventual spray drying.
5. Such a process also requires the use of sodium based emulsifying salts, resulting in increased sodium levels in the end product.
6. Heat treatment associated with rendering macerated cheese and other formulated ingredients causes substantial flavour losses due to the volatility of most naturally occurring cheese flavour compounds, because of the absence in the mix of sufficient suitable proteins or other encapsulating substances, which would prevent their escape.
7. Furthermore, the extent of heat treatment required for rendering, emulsifying and pasteurising the mix tends to further denature the available protein, and may cause oiliness, eventual flavour deterioration due to oxidation of the fat, and a tendency for the powder to lump under storage conditions.
It is an object of the invention to provide an improved process for the production of cheese flavour powder.
The invention accordingly provides a process for manufacturing cheese flavour powder comprising:
storing a volume of unpasteurized whole milk under substantially continuous agitation for a time and at a temperature such as to accelerate lipolysis of triglycerides in the milk by enzymes naturally present in the milk to release short chain fatty acids, including at least butyric, caproic, caprylic and capric acids and their derivative aldehydes and ketones, which are the principal components of cheese flavour;
then heating the milk to a temperature sufficient to substantially de-activate said enzymes and thus cause said lipolysis to substantially cease, and to cause previously uncoagulated whey protein naturally occurring in the unpasteurized milk to encapsulate said short chain fatty acids and their derivative aldehydes and ketones, thereby facilitating subsequent conversion to powder; and
converting the resultant product to a powder.
The invention is also directed to a cheese flavour powder in which the components of the cheese flavour, being the short chain fatty acids butyric caproic, caprylic and capric acids and their derivative aldehydes and ketones, are encapsulated by uncoagulated whey proteins. In a preferred aspect, the invention affords a cheese flavour powder manufactured by the aforedescribed process.
Using this process, it is possible to substantially reduce the use of cheese and hence the attendant storage and handling problems. The short chain fatty acids, which together with their derivative aldehydes and ketones are the principal components of cheese flavour and comprise in particular butyric, caproic, caprylic and capric acids, are volatile and liable to be readily lost in processing involving cheese maturing, storage and maceration, but are preserved and enhanced in the final product by processing directly into cheese flavour powder in accordance with the invention. The inventors have appreciated that, of the components identified at various times with cheese flavour, it is the specified short chain fatty acids and their derivatives which are the dominant determinants of a rounded cheese flavour. Moreover, the process of the invention avoids the coagulation of the milk proteins which normally occurs in the manufacture of cheese. Whey proteins in particular, because of their long chain hydrophilic structure, are excellent encapsulants and an adequate level of such material is essential for the successful retention of flavour during conversion of the mix to a dried powder. Without effective encapsulating material most volatile cheese flavouring acids would be lost in subsequent processing and storage. Because of the absence of adequate contained encapsulating material, the traditional process for the production of cheese flavour powder requires the addition of emulsifiers, such as sodium based emulsifying salts, which result in undesirable levels of sodium or call for expensive caseinate ingredients.
As indicated, the inventive process includes treating unpasteurized whole milk to enhance lipolysis of the triglycerides in the milk. A preferred novel feature of the invention is the utilisation for this purpose of the enzymes naturally present in the milk, for example naturally occurring enzymes or incidental bacterial enzymes, and particularly the lipolytic enzymes capable of hydrolysing fats and oils and thus liberating fatty acids including the aroma producing short chain fatty acids present in the milk fat. Because of possible health hazards, milk for public consumption, including most milk for cheese manufacture, has to be subjected to pasteurisation, a heat treatment designed to destroy pathogenic micro-organisms which may be incidentally present in the milk. It happens, however, that the pasteurisation treatment either substantially or totally inactivates the lipolytic enzymes and also other beneficial bacterial enzymes present in the milk, thus rendering the milk substantially inert as a medium for biochemical change.
This deleterious affect of pasteurisation on cheese flavour has been recognised and to counteract it, lipolytic enzyme preparations, derived from kids' or lambs' throat glands, have been introduced as additives to the milk in the manufacture of numerous cheese varieties, in order to promote the release of the short chain fatty acids, necessary for a full cheese flavour spectrum. In accordance with the invention, however, such additions are unnecessary as raw i.e. unpasteurised milk is treated to enhance lipolysis: pasteurisation can be effected if desired at any later convenient stage.
As indicated, the other principal feature of the invention is the utilisation of whey proteins as an encapsulating material, which, being non-volatile, holds the volatile flavour components within the product. Because the whey proteins are not coagulable by rennet, most of them are lost in the whey in the traditional cheese making process and therefore are not present in the cheese in sufficient amounts to serve as flavour encapsulants. Yet, because of their nature, they are eminently suitable for this function. In fact, they are considered more effective than most of the gums employed by flavour essence manufacturers for this purpose. But it is not only the structure of the whey proteins that renders them so useful for encapsulation. It is also their response to heat: the colloidal particles of the whey proteins tend to coalesce when heated. The invention provides a process by which this potential utility of the natural whey proteins can be realized.
In the process of coalescing, the whey proteins aggregate, locking within their framework the free cheese flavour components and thus preventing their escape into the atmosphere.
It is known that the whey proteins have effectively encapsulated the butterfat component, including the specified short chain fatty acids and their derivatives, because:
1. The free flowing nature of the powder produced without need of emulsifying agents (dispersing agents) and without homogenisation indicates encapsulated fat. This can be confirmed by microscopic examination of the powder particles.
2. The resultant strong and rounded cheese flavour further indicates the retention of the highly volatile said free fatty acids and their derivative aldehydes and ketones.
Utilising temperatures below those known to coagulate whey proteins, produces a less intense cheese flavour powder which exhibits a tendency to lumping.
Microscopic examination of the powder reveals free fat, and analysis for the said fatty acids shows a significant reduction in levels from those achieved by processing within the required ranges of the invention.
3. Determination of Whey Protein Nitrogen Index by analysis (a recognised measurement of the amount of undenatured serum protein remaining in the powder) at the various process stages shows conclusively the coagulation of the proteins, thus effecting encapsulation as described.
In addition, determination of Solubility Index measurements show a decrease in solubility i.e. a reduction in soluble protein, when the inventive technique is applied. The use of lower temperatures results in a higher solubility indicating a reduced level of protein coagulation has occurred.
The proportion of the listed short chain fatty acids achieved by the lipolysis step is advantageously in the range 40-55 mg per kg of treated milk, most preferably 45-50 mg/kg.
Said substantially continuous agitation is preferably at least sufficient to disturb the surface of the milk but may be vigorous agitation, for example agitation by stirring sufficient to break the surface of the milk. It is normal practice to gently stir milk in storage with a slow blade, to prevent fat separation, but such stirring is not sufficient to disturb the surface of the milk. In the present process, agitation disrupts the fat globule membrane and facilitates the action of naturally occurring lipase enzyme in exerting a hydrolysing influence on the contained fat triglycerides, releasing the four short chain fatty acids and their derivative aldelydes and ketones.
A preferred temperature for accelerating lipolysis is in the range 6.degree.-15.degree. C. and a preferred storage period is in the range 6-16 hours. Normal milk storage temperature is 3-4.degree. C. Below 6.degree. C., the lipolysis process is unacceptably slow. If the temperature exceeds 15.degree. C. degradation such as uncontrolled fat splitting begins to occur: the butterfat re-agglomerates and lumps of butter begin to form. A storage period below 6 hours results in an inadequate level of lipolysis while storage for more than 16 hours results in the general quality of the milk deteriorating to unacceptable levels. Such lengthy storage is in any event of no additional advantage and thus becomes unjustifiable on economic grounds.